It is unfortunately a relatively common experience among many operators of motor vehicles that a well-maintained or even relatively new internal combustion engine cannot be started when the battery that supplies the power to the starter is discharged below a minimum power level needed to crank the engine. In many cases an external power source, such as a second battery, must be coupled to the discharged battery with jumper cables to provide auxiliary power to start the engine. However, such external power sources and/or cables may not be readily available. In addition, connecting jumper cables to a battery can be dangerous because the battery emits combustible gases, and a spark resulting from such a connection may ignite the gases. Furthermore, improper connection of the jumper cables between the auxiliary battery and the discharged battery can cause damage to the vehicle's electrical system.
Another common problem associated with motor vehicles is that the cranking battery used to start the internal combustion engine has reduced amp-hour capacity at low ambient temperatures due to the temperature sensitivity of the chemical reactions inherent in such batteries. This drawback, coupled with the typically greater cranking current required to overcome the increased internal friction of a cold engine, can result in a failure to start the engine, particularly if the battery has not been fully charged or suffers from reduced capacity due to battery aging.
Yet another concern is the high cranking current demanded of a battery during the starting cycle of an internal combustion engine. This high current demand can quickly and deeply discharge the battery, which adversely affects the capacity and life of the battery. There is a need for a way to utilize on-board supplementary power sources to provide auxiliary power to start the vehicle's engine and to charge the cranking battery when it is discharged.